Two-cycle internal-combustion engine



Oct. 1, 1963 c. KIEKHAEFER 3,105,474

TWO-CYCLE INTERNAL-COMBUSTION ENGINE Filed Feb. I23, 1961 2 Sheets-Sheet1 79 ,l W l5 28 27 5 4 INVENTOR. 29 ELMER G. KIEKAEFER 3 BY 2 ANDRUS 8:STARKE Unite This invention relates to two-cycle, internal-combustionengines and more particularly to the fuel intake and exhaust manifoldingof multi-cylinder, two-cycle engines.

Ordinarily the cylinders of a two-cycle engine, disposed in-line or in abank, all exhaust to one side of the cylinder block while the fuel forcombustion is received from the opposed side of the block. In operationthe exhaust side of the block becomes relatively hot while the intakeside remains relatively cool. The temperature differential betweenopposed sides of the block may reach as high as 500 F. introducingthermal stresses which may distort or otherwise damage engine parts. Itis generally an object of this invention to provide a twocycle enginestructure wherein the temperature difierential between opposed sides ofthe block is substantially reduced or virtually eliminated resulting ina substantial symmetry of thermal expansion as between the sides of theengine.

According to this invention, the block of a two-cycle,internal-combustion engine comprises at least one bank of a plurality ofcylinders disposed in line. Each cylinder of the bank is provided with afuel inlet and opposed exhaust outlet which open to the respective sidesof the bank. The fuel inlets and exhaust outlets of the severalcylinders respectively alternate on adjacent cylinders between therespective sides of the bank to provide a substantial symmetry ofthermal expansion from one side of the engine to the other.

The drawings furnished herewith illustrate the best mode of carrying outthe invention as presently contemplated and set forth hereinafter.

In the drawings:

FIG. 1 is a side elevation with parts broken away and sectioned of atwo-cycle, internal-combustion engine which embodies the invention;

FIG. 2 is a section taken generally on line 22 of the engine of FIG. 1;and

FIG. 3 is a section taken generally on line 33 of FIG. 2.

Referring to the drawings, the multi-cylinder, two-cycle engine 1 isshown mounted on the upper end of a drive shaft housing 2 of an outboardmotor, not shown, and includes the crankcase member 3 and cylinder block4 which are secured together by a plurality of bolts 5 to provide aclosed crankcase 6. The crankshaft 7 extends vertically through thecrankcase 6 and is journally supported within suitable bearing units 8disposed at the upper and lower extremities of the engine betweencrankcase member 3 and the cylinder block 4. The crankshaft 7 carriesthe flywheel 9 at the upper end thereof and is drivingly connected atthe lower end thereof to a drive shaft 11) extending downwardly withinthe drive shaft housing 2.

The multi-cylinder engine 1 is shown as having a bank of four in-linecylinders 11, 12, 13 and 14 within each of which a piston 15 is slidablydisposed. A connecting rod 16 connects the respective pistons 15 to thecorresponding cranks '17 spaced longitudinally of the crankshaft 7. Thecranks 17 are spaced angularly with respect to the axis of crankshaft 7to provide the desired firing order for the respective cylinders.

Upper and lower bearing members 18, disposed intermediate cranks 17 forthe upper and lower pairs of cylin- 3,l5,474 Patented Get. 1, 1963 ders,and the central bearing member 19 are disposed in the crankcase 6 anddivide the crankcase into separate crankcase chambers 20 correspondingto the respective cylinders. Each bearing member 18 is provided with afuel induction passage 21 which opens into the adjacent chambers 20through suitable ports, not shown, controlled by reed valves 22. Thefuel mixture for engine combustion enters passage 21 from a carburetor23 carried by the crankcase member 3.

'In the operation of the engine 1, the valves 22 control the flow offuel mixture into the chambers 2t) in accordance with piston travel. Thevalves are opened for induction of fuel into a given chamber 2t) witheach upstroke of the corresponding piston 15 and closed during eachdownstroke of the piston. The downwardly moving piston effects aprecompressionof the fuel charge drawn into the chamber 20.

The respective cylinders are provided with fuel inlet ports 24 whichopen into a corresponding transfer passage 25. The transfer passages 25are formed in the cylinder block 4 and project into and extend througheither of the exhaust cavities 26 and 27 as will be explainedhereinafter. Each passage 25 extends adjacent and generally parallel tothe corresponding cylinder and places the cylinder in communication withthe corresponding crankcase chamber 24}. As shown in the drawings, theinlet ports 24 and the transfer passages 25 alternate to opposed sidesof the cylinder bank as between adjacent cylinders in the bank.

Each of the respective cylinders of engine 1 are provided with exhaustports 28 in the wall of the cylinders oppositely from the inlet ports24. The exhaust ports 28, like inlet ports 24, alternate to opposedsides of the cylinder bank as between adjacent cylinders in the bank andopen into exhaust cavities 26 and 27 formed in the block 4 on therespective sides of the bank of cylinders. Exhaust cavities 26 and 27are closed off by water-cooled plate assemblies 29 and communicate withthe drive shaft housing 2 which conducts the exhaust products from theengine 1.

With the exhaust ports 28 of adjacent cylinders in engine 1 opening toopposed sides of the cylinder block into exhaust chambers 26 and 27respectively, the relatively hot exhaust products from the enginecylinders move to both sides of the block 4 for conduction from theengine. As a result, the respective sides of engine 1 are substantiallyuniformly heated by the exhaust gases to provide a substantial symmetryor balance of thermal expansion from one side of the engine to the otherand substantially eliminate problems due to distortion of engine parts.

Since the fuel inlets 24 of adjacent cylinders also alternate to opposedsides of the cylinder block 4, the thermal balance from one side of theengine to the other remains undisturbed. With the transfer passages 25projecting into the exhaust chambers 26 and 27, a heat interchange maybe expected to take place between the relative hot exhaust gases withinthe chambers and the relatively cool fuel mixture moving within thepassages to enhance engine efiiciency.

The arrangement of this invention with the exhaust ports 28 of adjacentcylinders opening to opposed sides of the cylinder bank, oifers moreroom than is ordinarily available in engines where the exhaust ports allopen to one side of the block so it becomes physically pos sible tobring out separate exhaust pipes for each cylinder if it is desired totune the exhaust of each cylinder to attain maximum power output. Itwill be noted, too, that the arrangement of this invention results in anengine structure which is equally wide to either side of a plane throughthe axis of the several cylinders in the 3 bank which is of considerableassistance when designing and styling a cowl for the engine.

Various modes of carrying out the invention are contemplated as beingWithin the scope of the following claims particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

I claim:

1. In a two-cycle internal-combustion engine having at least one bank ofa plurality of cylinders disposed in line, each cylinder having afuel'inlet and opposed exhaust outlet in the cylinder wall opening tothe respective sides of the bank, said fuel inlets and exhaust outletsrespectively alternating on adjacent cylinders between the respectivesides of the bank to provide for substantial symmetry of thermalexpansion from one side of the engine to the other in operation.

2. In a two-cycle internal-combustion engine, a cylinder block having abank of a plurality of cylinders dis-.

posed in line and an exhaust cavity on each side of the cylinder bank,each cylinder having a fuel inlet and an exhaust outlet, said exhaustoutlets respectively alternating on adjacent cylinders between therespective sides of the bank and opening into the corresponding exhaustcavity to provide for a substantial symmetry of thermal expansion fromone side of the engine to the other in op eration.

3. The invention as set forth in claim 2 wherein the fuel inlet for eachcylinder is disposed oppositely from the exhaust outlet.

4. In a two-cycle internal-combustion engine, a crankcase, a cylinderblock adapted to be joined to the crankcase and having a bank of aplurality of cylinders disposed in line and an exhaust cavity on eachside of the cylinder bank, said crankcase having separate chamberscorresponding to each cylinder and said chambers being adapted toreceive a fuel mixture for precompression, each cylinder having a fuelinlet and opposed exhaust outlet, said fuel inlet and exhaust outletrespectively alternating on adjacent cylinders between the respectivesides of the bank and said exhaust outlets opening into the respectiveexhaust cavities, and transfer passages respectively connecting thecrankcase chambers and fuel inlet of the corresponding cylinders forconducting the fuel mixture to the cylinders and extending through theexhaust cavities, said passages and adjacent exhaust cavities placingthe relatively cool fuel mixture and the relatively hot exhaust gasesinto heat interchange relationship whereby to enhance engine efiiciency.

References Cited in the file of this patent UNITED STATES PATENTSBarkeij Apr. 30, 1940 2,199,276 2,216,491 Grantz et al Oct. 1, 19402,643,510 Kiekhaefer June 30, 1953

1. IN A TWO-CYCLE INTERNAL-COMBUSTION ENGINE HAVING AT LEAST ONE BANK OFA PLURALITY OF CYLINDERS DISPOSED IN LINE, EACH CYLINDER HAVING A FUELINLET AND OPPOSED EXHAUST OUTLET IN THE CYLINDER WALL OPENING TO THERESPECTIVE SIDES OF THE BANK, SAID FUEL INLETS AND EXHAUST OUTLETSRESPECTIVELY ALTERNATING ON ADJACENT CYLINDERS BETWEEN THE RESPECTIVESIDES OF THE BANK TO PROVIDE FOR SUBSTANTIAL SYMMETRY OF THERMALEXPANSION FROM ONE SIDE OF THE ENGINE TO THE OTHER IN OPERATION.